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Cerium Anomalies and Paleoredox

Cerium Anomalies and Paleoredox PDF Author: Rosalie Tostevin
Publisher: Cambridge University Press
ISBN: 9781108810739
Category : Science
Languages : en
Pages : 75

Book Description
Ce anomalies track changes in oxygen availability due to the anomalous redox-sensitivity of Ce compared with the other rare earth elements. The proxy systematics have been calibrated experimentally as well as in modern anoxic water bodies. Ce anomalies are unique because they track intermediate manganous conditions, rather than fully anoxic conditions. In addition, they are sensitive to local-regional redox conditions, and can be analysed in chemical sediments such as carbonate rocks. This makes them especially useful as a tool to track local oxygen distribution in shallow shelf environments, where biodiversity is highest. This review focusses on the systematics of the Ce anomaly proxy, the preservation and extraction of the signal in sedimentary rocks, and the potential applications of the proxy.

Cerium Anomalies and Paleoredox

Cerium Anomalies and Paleoredox PDF Author: Rosalie Tostevin
Publisher: Cambridge University Press
ISBN: 9781108810739
Category : Science
Languages : en
Pages : 75

Book Description
Ce anomalies track changes in oxygen availability due to the anomalous redox-sensitivity of Ce compared with the other rare earth elements. The proxy systematics have been calibrated experimentally as well as in modern anoxic water bodies. Ce anomalies are unique because they track intermediate manganous conditions, rather than fully anoxic conditions. In addition, they are sensitive to local-regional redox conditions, and can be analysed in chemical sediments such as carbonate rocks. This makes them especially useful as a tool to track local oxygen distribution in shallow shelf environments, where biodiversity is highest. This review focusses on the systematics of the Ce anomaly proxy, the preservation and extraction of the signal in sedimentary rocks, and the potential applications of the proxy.

Cerium Anomalies and Paleoredox

Cerium Anomalies and Paleoredox PDF Author: Rosalie Tostevin
Publisher: Cambridge University Press
ISBN: 1108847579
Category : Science
Languages : en
Pages : 46

Book Description
Ce anomalies track changes in oxygen availability due to the anomalous redox-sensitivity of Ce compared with the other rare earth elements. The proxy systematics have been calibrated experimentally as well as in modern anoxic water bodies. Ce anomalies are unique because they track intermediate manganous conditions, rather than fully anoxic conditions. In addition, they are sensitive to local–regional redox conditions, and can be analysed in chemical sediments such as carbonate rocks. This makes them especially useful as a tool to track local oxygen distribution in shallow shelf environments, where biodiversity is highest. This review focusses on the systematics of the Ce anomaly proxy, the preservation and extraction of the signal in sedimentary rocks, and the potential applications of the proxy.

Trace Elements in Waterlogged Soils and Sediments

Trace Elements in Waterlogged Soils and Sediments PDF Author: Jörg Rinklebe
Publisher: CRC Press
ISBN: 1482240521
Category : Science
Languages : en
Pages : 419

Book Description
Many wetlands around the world act as sinks for pollutants, in particular for trace elements. In comparison to terrestrial environments, wetlands are still far less studied. A collaborative effort among world experts, this book brings the current knowledge concerning trace elements in temporary waterlogged soils and sediments together. It discusses factors controlling the dynamics and release kinetics of trace elements and their underlying biogeochemical processes. It also discusses current technologies for remediating sites contaminated with trace metals, and the role of bioavailability in risk assessment and regulatory decision making. This book is intended for professionals around the world in disciplines related to contaminant bioavailability in aquatic organisms, contaminant fate and transport, remediation technologies, and risk assessment of aquatic and wetland ecosystems.

Iron-Formation: Facts and Problems

Iron-Formation: Facts and Problems PDF Author: A.F. Trendall
Publisher: Elsevier
ISBN: 008086905X
Category : Science
Languages : en
Pages : 559

Book Description
Iron-Formation: Facts and Problems

Molybdenum as a Paleoredox Proxy

Molybdenum as a Paleoredox Proxy PDF Author: Stephan R. Hlohowskyj
Publisher: Cambridge University Press
ISBN: 1009002260
Category : Science
Languages : en
Pages : 57

Book Description
Molybdenum (Mo) is a widely used trace metal for investigating redox conditions. However, unanswered questions remain that concentration and bulk isotopic analysis cannot specially answer. Improvements can be made by combining new geochemical techniques to traditional methods of Mo analysis. In this Element, we propose a refinement of Mo geochemistry within aquatic systems, ancient rocks, and modern sediments through molecular geochemistry (systematically combining concentration, isotope ratio, elemental mapping, and speciation analyses). Specifically, to intermediate sulfide concentrations governing Mo behavior below the 'switch-point' and dominant sequestration pathways in low oxygen conditions. The aim of this work is to 1) aid and improve the breadth of Mo paleoproxy interpretations by considering Mo speciation and 2) address outstanding research gaps concerning Mo systematics (cycling, partitioning, sequestration, etc.). The Mo paleoproxy has potential to solve ever complex research questions. By using molecular geochemical recommendations, improved Mo paleoproxy interpretations and reconstruction can be achieved.

Black Shales

Black Shales PDF Author: P. B. Wignall
Publisher:
ISBN:
Category : Nature
Languages : en
Pages : 152

Book Description
Black shales provides the first comprehensive synthesis of the diverse research regarding the origin of petroleum source rocks. The book offers in-depth reviews from the fields sedimentology, palaeoecology, and geochemistry, and particularly focuses on the influence of palaeo-oxygen levels. Current debates--including the one over the influence of sedimentation rate, productivity, and enhanced preservation on the burial efficiency of organic carbon--receive a lively discussion. In addition, the importance of newly defined concepts of sequence stratigraphy to models of the formation of black shales receives an in-depth treatment for the first time. The book will be of interest to all geologists investigating palaeoenvironments, particularly those engaged in the search for hydrocarbons.

Reconstructing Precambrian pCO2 and pO2 Using Paleosols

Reconstructing Precambrian pCO2 and pO2 Using Paleosols PDF Author: Nathan D. Sheldon
Publisher: Cambridge University Press
ISBN: 1108876811
Category : Science
Languages : en
Pages : 38

Book Description
Paleosols formed in direct contact with the Earth's atmosphere, so they can record the composition of the atmosphere through weathering processes and products. Herein we critically review a variety of different approaches for reconstructing atmospheric O2 and CO2 over the past three billion years. Paleosols indicate relatively low CO2 over that time, requiring additional greenhouse forcing to overcome the 'faint young Sun' paradox in the Archean and Mesoproterozoic, as well as low O2 levels until the Neoproterozoic. Emerging techniques will revise the history of Earth's atmosphere further and may provide a window into atmospheric evolution on other planets.

Vanadium Isotopes

Vanadium Isotopes PDF Author: Sune G. Nielsen
Publisher: Cambridge University Press
ISBN: 9781108797948
Category : Science
Languages : en
Pages : 75

Book Description
Vanadium isotope ratios (51V/50V) have potential to provide information about changes in past ocean oxygen contents. In particular, V isotopes may find utility in tracing variations at non-zero oxygen concentrations because the redox couple that controls V elemental and isotopic abundances in seawater (vanadate-vanadyl) appears to operate around 10M O2. This characteristic sets V isotopes apart from many other metal isotope redox proxies that require more reducing conditions to register significant changes in their isotope budgets. The oxygen abundance sensitivity range of V isotopes suggests that this paleoproxy could be particularly useful in tracing marine oxygenation changes throughout the Phanerozoic and potentially beyond.

Precambrian Banded-Iron-Formations

Precambrian Banded-Iron-Formations PDF Author: Y.P. Mel'nik
Publisher: Elsevier
ISBN: 0080869041
Category : Science
Languages : en
Pages : 323

Book Description
Precambrian Banded-Iron-Formations

Local and Global Controls on Carbon Isotope Chemostratigraphy

Local and Global Controls on Carbon Isotope Chemostratigraphy PDF Author: Anne-Sofie Ahm
Publisher: Cambridge University Press
ISBN: 100903362X
Category : Science
Languages : en
Pages : 48

Book Description
Over million-year timescales, the geologic cycling of carbon controls long-term climate and the oxidation of Earth's surface. Inferences about the carbon cycle can be made from time series of carbon isotopic ratios measured from sedimentary rocks. The foundational assumption for carbon isotope chemostratigraphy is that carbon isotope values reflect dissolved inorganic carbon in a well-mixed ocean in equilibrium with the atmosphere. However, when applied to shallow-water platform environments, where most ancient carbonates preserved in the geological record formed, recent research has documented the importance of considering both local variability in surface water chemistry and diagenesis. These findings demonstrate that carbon isotope chemostratigraphy of platform carbonate rarely represent the average carbonate sink or directly records changes in the composition of global seawater. Understanding what causes local variability in shallow-water settings, and what this variability might reveal about global boundary conditions, are vital questions for the next generation of carbon isotope chemostratigraphers.